(1) Field of the Invention
The present invention relates to an area judging apparatus for judging multiple areas of character portions, photograph portions, halftone dot portions and the like of the image in digital copying machines, digital printers, digital facsimile machines or the like.
(2) Description of the Prior Art
It is necessary to perform the optimum processing according to the properties of the original document image in order to realize the high quality of the recorded image. For that purpose, in the case of an original document in which character portions, photograph portions and halftone dot portions coexist together, area judgement is performed. In such case, the accuracy of the judgement becomes an important problem.
As a method for judging the halftone (dot) photograph and the character area, there is proposed a method in which after performing a processing for emphasizing the coefficient of a high frequency domain by the filtering processing, and binarizing into binary value, judgement is performed depending upon the presence or absence of closed areas of white or black in a predetermined area (see Japanese Patent Publication Hei 5 No. 28944).
In the above Japanese Patent Publication Hei 5 No. 28944, however, only a judgement if it is a halftone (dot) photograph area or a character area is performed for a predetermined area unit (for example, minimum 3 pixels.times.3 pixels). Therefore, fine judgement of multiple areas such as a character area, a photograph area, or a halftone dot area cannot be performed.